1. Field of the Invention
The present invention relates to a plating jig for performing electroless plating applied to a wafer.
2. Description of the Related Art
In recent years, plating technology has extensively been applied to various fields of technologies, such as one which utilizes wiring for semiconductor chips. In the field of semi-conductor-related industries, wiring pitches are required to be reduced to accomplish high integration and performance. For example, in a wiring technology employed in latest years, wiring grooves are generated on an oxide film formed on a silicon wafer in a dry etching process. The wiring grooves are plated, wherein a wiring material is embedded.
According to a method of plating such an object to be plated as the wafer and the like, JP2002-327291A discloses an electroplating method, wherein an anode plate is disposed opposite to a surface to be plated of an object to be plated immersed in a plating solution, fresh plating solution is jetted to the surface to be plated, and the surface to be plated is plated by energizing between the surface to be plated and the anode plate.
However, the process of forming a plated layer generally takes some time. The conventional electroplating method is required to conduct a series of operations for each object to be plated, and is not suitable for shortening and streamlining operations for a processing of plating in which a number of objects to be plated are plated.
As shown in FIG. 7, JP2002-339078A discloses an electroless plating jig 110, whereby enabling a surface 121 to be plated of a wafer 120, which is an object to be plated, to be exposedly supported. The plural number of the electroless plating jigs 110 are piled on a top of another, connected, and immersed in plating solution 131 pooled in a plating tank 130 so as to perform electroless plating.
However, the plating solution 131 in the plating tank 130 generates hydrogen in the process of plating. Accordingly, the higher the density of hydrogen becomes, the nearer to the surface of the plating solution the depth of the plating solution becomes in the plating site. Therefore, according to the electroless plating method, in which the conventional plating jig 110 is used, the thicknesses of electroplated films formed on the wafer 120 disposed at a shallow depth and the wafer 120 disposed at a deep depth become inhomogeneous.
The temperature of an upper part of the plating solution 131 becomes higher than that of a lower part of the plating solution 131. Accordingly, the velocity of forming a plated film on the wafer 120 disposed in the upper part of the plating solution 131 is higher than that of forming the plated film on the wafer 120 disposed in the lower part of the plating solution 131. The thicknesses of the plated films formed on the wafers 120 disposed in the upper part and the lower part of the plating solution 131 become inhomogeneous.